Production of abrasive material



Reissued Sept. 10, 1940 UNITED STATES PATENT OFFICE PRODUCTION OFABRASIVE MATERIAL Raymond C. Benner and Romie L. Melton, Niagara Falls,N. Y, assignors, by mesne assignments, to The Carborunduml Company,Niagara Falls, N. Y., a corporation of Delaware No Drawing. Original No.2,0'l8,831. dated April 27, 1931, Serial No. 56,704, December so, 1935.Application for reissue May 9, 1940, Serial No.

ticles and methods of manufacturing the same. More specifically theinvention is concerned with coated abrasive products such as abrasivesheets.

belts, disks and the like.

The use of resinous products in the manufacture of coated abrasivearticles has been proposed previously but, the use of these materials isretarded because they require a long heat treatment to set up or curethe resins to a point where they bond the abrasive grains to the backingwith sufficient strength. This is a disadvantage in that-prolonged heattreatment weakens the backing material such as paper and cloth commonlyemployed in the manufacture of coated abrasives, and the speed at whichabrasive paper machines are operated require that a very considerablequantity of material be stored up, as in festoons, when the material hasto be treated for a long time to set up the binder.

. We have discovered that if coated abrasive products employing a bindercontaining a synthetic resin are subjected to the action of certaincatalysts the hardening of the resin binder is very materially hastened.In some cases resins may be hardened completelyv at ordinary roomtemperatures when catalysts are added and in other cases a heattreatment is employed to still further hasten the hardening process.This heat treatment may be at a much lower temperature than ordinarilyrequired to cure the resin. In general the action of the catalyst isincreased by a rise in temperature, but in any event it is possibletoreduce the time and temperature required to set up the resinous materialto such an extent that the use of these resinous binders is economicallypractical.

We will now illustrate our invention with a number of specific examples,it being understood that these examples are for purposes of illustrationonly.

\ Example I (Cl. 51-298) F. for about 30 seconds to harden the resincoating and attach the abrasive grains firmly to the backing material.

Example II Fabric coated with liquid phenol formaldehyde resin andabrasive grains as in Example I has applied to the coated surfacethereof a thin coating of a solution of 5 grams of aluminum chloride in125 cc. of ethyl alcohol by suitable means, for example by means of aspray. The coated fabric is then heated for approximately 1 minute at300? F. in which time the resin sets'up to a hard film which efiectivelyattaches the abrasive grains to the backing. The coated paper is thenwound into a roll.

Example III A backing such as paper or cloth is coated with a varnish ofan oil-extended phenol-modi fied alkyd resin and abrasive grains in theusual manner. The coated surface is then treated, e. g.

Example I V A backing material is coated with abrasive grains and apetroleum naphtha solution of an alkyd resin free from phenol or resinmodifying agents. The coated surface is then treated,

e. g. sprayed, with a solution of about 1 part of sulphuric acid inabout 40 parts of ethyl alcohol. The article is heated to 300 F. for oneminute. After this treatment the film is non-tacky and flexible and insuch condition that the coated backing can be rolled up and given anadditional hardening treatment.

Example V A normally liquid phenol formaldehyde condensation product.containing 2% of ferric ch1o ride ground in the resin is applied to abacking material and abrasive grains then distributed over the resincoating. The article may then be allowed to stand for about 7 days atroom temperature ('70 to F.)' at theend of which time it will be foundthat the resin has set up to a firm solid consistency, attaching thegrains to the backing. The article may then be wound into a roll andheat treated to cure the resin.

Example VI A making coat of adhesive made according to the followingformula:

Grams Phenol-aldehyde casting resin 1300 Liquid acid catalyst 104Denatured alcohol 130 is applied to a backing which may be 130# cylinderpaper, at the rate of 1.8 lbs. per ream. 80 grit fused alumina isdistributed thereon at the rate of 19.5 lbs. per ream. The thus coatedpaper is cured for about four hours at room temperature and one hour atabout 70 C. The coated and then air-dried over night and then curedabout two hours at about 70 C. This method has the advantage over priormethods that the low temperature cure made possible by the catalyst doesnot harm the backing.

As illustrated by the examples our invention is subject to a number ofmodifications. For example, the catalyst may be mixed in with theresinous material, in which case it should be applied to the backingwithin a few hours, or the resin may be spread over the backing and thecatalyst then applied to the resin film. The resin coating may also becured in an atmosphere containing a catalyst such as gaseoushydrochloric acid. The catalyst may also be added with the grain, as apowder mixed with or attached to the grain or as a solution moisteningthe grain. It is also within the scope of the invention to rely entirelyon the action of the catalyst under ordinary temperature conditions orthe article may be heated to hasten the hardening of the resin. We havealso found it desirable at times to subject the article to a heattreatment while the web of material is being fed through the abrasivemaking machine, as for example, by passing the coated side of thesurface under suitable heating elements such as electrical heaters,followed by further heat treatment of the article after it has beenwound into a roll.

Catalysts other than those specifically mentioned in the examples havebeen found to be suitable, including both acids and bases, as well asso-called acid salts such as aluminium chloride or ferric chloride.

It is also within the scope of our invention to selectively vary thestiffness and flexibility of the finished material by varying the kindand quantity of catalyst and the time and temperature of heat treatment.For example in the above illustrations the time of curing may belengthened to produce a. more brittle article and the quantity ofcatalyst may be reduced to produce a more flexible article.

We claim:

1. The method of making abrasive coated products which comprises coatinga backing material with a liquid resin and applying abrasive grains anda catalyst for curing the resin to the resin coated side of the backingto cause the resin to solidify and attach the abrasive grains firmly tothe backing. v

2. The method of making abrasive coated products which comprises coatinga backing material with abrasive grains and a liquid resinous materialand applying a coating of liquid con- I taining a catalyst for curingthe resin to the coating on the backing to cause the resin to solidifyand attach the abrasive grains firmly to the backing.

3. The method of making abrasive coated products which comprises coatinga backing material with abrasive grains and a normally liquid phenoliccondensation product and applying a catalyst to the resin coating tocause the liquid resin to solidify and attach the abrasive grains firmlyto the backing.

4. The method of making abrasive coated products which comprises coatinga backing material with abrasive grains and a normally liquid alkydresin and applying a catalyst to the resin coating to cause the liquidresin to solidify and attach the abrasive grains firmly to the backing.

5. The method of making abrasive coated products which comprises coatinga backing material with abrasive grains and an oil varnish containing aphenol-modified alkyd resin, and applying a catalyst for the resin tothe varnish to cause the varnish to harden and attach the abrasivegrains firmly to the backing.

6. In the manufacture of abrasive coated products the steps whichcomprise coating a backing material with abrasive grains, a liquidresinous material, and a catalyst of acid character which is adapted tosolidify the liquid resinous material at ordinary temperatures, andsolidifying the binder.

'7. In the manufacture of abrasive coated articles in which a backing iscoated with abrasive grains that are confined to the backing byanadhesive coating, the improved method which comprises bringing a liquidresin of the type which may be cured at an accelerated rate by acatalyst, to a condition of suitable coating viscosity, applying saidresin so prepared and a suitable catalyst, which will accelerate thecuring of said resin, to a backing, and then applying a" coat ofabrasive grains to said resinous layer on said backing while saidresinous layer is in an adhesive condition.

8. In the manufacture of abrasive coated articles in which a backing iscoated with abrasive grains that are confined to the backing by anadhesive coating, the improvement therein which comprises bringing to acondition of suitable coating viscosity, a normally liquid, syntheticresin 01' a type which is relatively stable at ordinary temperatures andcapable of advancing to a more advanced stage of curing at a relativelyslow rate at elevated temperatures, coating said backing with saidprepared resin,- applying to said layer a catalyst capable of hasteningthe curing of said resin, and abrasive grains, and subsequentlysubjecting the abrasive coated backing to conditions that advance thecuring of said resin with the aid of said catalyst.

9. In the manufacture of abrasive coated articles in which a backing iscoated with abrasive grains that are confined to the backing by anadhesive coating the improvement therein which comprises applying tosaid backing a layer of a liquid, resinous material of the type which isrelatively stable at ordinary temperatures and capable of acceleratedadvancement to a more advanced stage of curing under the influence of acatalyst, applying to said layer a catalyst, and a layer of abrasivegrains, subjecting the coated backing to conditions that advance thecuring of said resinous material with the aid of said catalyst to astage less than full curing, then applyin: to the backing so preparedanother liquid coating of such a ruinous material. a solvent thereforand a catalyst for said resinous material, and subsequently subjectingthis additionally coated backing to conditions that further advance thecuring of said resinous materials with the aid of said catalysts.

mmorm 0. 31mm. 5 noun: n amn on.

